[Intel-gfx] [PATCH 2/3] drm/i915: Enable FIFO underrun reporting after initial fastset

[Maarten Lankhorst]

Op 08-11-17 om 16:38 schreef Daniel Vetter:
> On Wed, Nov 08, 2017 at 10:29:21AM +0100, Maarten Lankhorst wrote:
>> The firmware may have set up the pipe correctly, but the FIFO
>> underrun and CRC interrupts are likely not enabled.
>>
>> This resulted in debugfs_test.read_all_entries failing on haswell,
>> because of a timeout when reading the crc debugfs entry.
>>
>> Solve this by enabling FIFO underrun reporting after the initial
>> fastset, which lets interrupts be generated as expected.
>>
>> Testcase: debugfs_test.read_all_entries
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_display.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index 737de251d0f8..8d42e6a910d4 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -12875,6 +12875,7 @@ static void intel_begin_crtc_commit(struct drm_crtc *crtc,
>>  static void intel_finish_crtc_commit(struct drm_crtc *crtc,
>>  				     struct drm_crtc_state *old_crtc_state)
>>  {
>> +	struct drm_i915_private *dev_priv = to_i915(crtc->dev);
>>  	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>>  	struct intel_atomic_state *old_intel_state =
>>  		to_intel_atomic_state(old_crtc_state->state);
>> @@ -12882,6 +12883,15 @@ static void intel_finish_crtc_commit(struct drm_crtc *crtc,
>>  		intel_atomic_get_new_crtc_state(old_intel_state, intel_crtc);
>>  
>>  	intel_pipe_update_end(new_crtc_state);
>> +
>> +	if (HAS_PCH_SPLIT(dev_priv) && new_crtc_state->update_pipe &&
> The HAS_PCH_SPLIT looks very wrong. Just enable fifo underrun reporting
> already for the relevant pipes. I think really the only check you need
> here is for I915_MODE_FLAG_INHERITED and then the has_pch_encoder check
> too. Everything else looks like cargo culting conditions.
Agree, I'll drop the HAS_PCH_SPLIT check part, has_pch_encoder && !HAS_DDI should be enough. :-)
> Note that at driver boot-up _all_ fifo underrun reporting is disabled by
> default, so we really need to enable it everywhere explicitly.
>
> Placement looks good since it's after the wm update. That's really the
> only reason we don't enable it straight at driver load, since we don't
> entirely trust the firmware wm settings.
Yes. :)